Drive shaft balancing machines are known, inter alia, from DE 28 02 367 B2 and U.S. Pat. No. 6,694,812 B2. In drive shaft balancing machines, the drive shafts to be balanced are received at either end by a rotary spindle of a pedestal. The spindle is carried in a bearing housing supported on the pedestal by means of springs. The springs, which are generally leaf springs, are arranged in a way enabling the upper part to vibrate as a result of parallel displacement of its spindle axis and responding only to transverse forces produced by an imbalance of the drive shaft and transmitted to the upper part through the joints and the spindle. Considering that the joints of the drive shaft transmit no bending moments, the pedestals of drive shaft balancing machines are configured as unbalance measuring devices for a single plane, with one vibration sensor being arranged on each pedestal to detect the vibrations of the pedestal upper part in the degree of freedom of motion normal to the spindle axis. This configuration has since been proven in practice.
In a crankshaft balancing machine known from DE 15 73 670 B2, the bearing bracket of a pedestal is carried on two vibration-detecting force transducers having different measuring directions lying in the bearing plane. The signals of the two force transducers are split up by evaluating circuits according to their Cartesian vibration components, from which the circular and polar or anti-circular components are represented.
JP 57 165 731 A discloses an imbalance correcting system in which the rotor is carried in two bearings by means of bearing pins. Each bearing includes a first vibration sensor for detecting the vibrations of the bearing pin and, spaced therefrom, a second vibration sensor measuring in the same direction as the first one and detecting vibrations of coupling parts arranged at the end of the bearing pin.